Aura MLS


Contact: William Read

Relative humidity with respect to ice (RHI) is the ratio of the amount of water vapor present to the maximum amount of water vapor that a parcel of air can hold (adding more water will lead to ice condensation with no change increase in humidity - strongly dependent on the air parcel's temperature).

RHI is measured in units of percent. It is useful for determining where clouds are present or likely to form. Both humidity and clouds exert significant radiative forcings in the Earth Climate System.

How it is part of MLS Science Objectives

One of the scientific objectives of MLS is studying climate change. MLS measurements of relative humidity along with temperature and cloud ice are important for improving our understanding climate processes.

How EOS MLS derives RHI

RHI is relative humidity with respect to ice. It is a derived product from the standard products of water vapor and terperature using the Goff-Gratch formula.

Quick Product Information for data version v5

  • Swath Name: RHI
  • Status Flag: Only use profiles for which the Status field is an even number.
  • Useful Range: Profile from 316 - 0.001 hPa
  • DAAC Short Name: ML2RHI
  • Quality Threshold: See v5 data quality document.
  • Convergence Threshold: < 2.0; Temperature Convergence < 1.03

Download Aura MLS RHI v5 data

Latest Publications (RHI)

  1. Dion, I., P. Ricaud, P. Haynes, F. Carminati and T. Dauhut
    Ice injected into the tropopause by deep convection – Part 1: In the austral convective tropics
    Atmos. Chem. Phys. doi:10.5194/acp-19-6459-2019, 2019
  2. Schoeberl, M.R., E.J. Jensen, L. Pfister, R. Ueyama, T. Wang, H. Selkirk, M. Avery, T. Thornberry and A.E. Dessler
    Water Vapor, Clouds, and Saturation in the Tropical Tropopause Layer
    Journal of Geophysical Research: Atmospheres doi:10.1029/2018jd029849, 2019
  3. Lambert, A. and M. Santee
    Accuracy and precision of polar lower stratospheric temperatures from reanalyses evaluated from A-Train CALIOP and MLS, COSMIC GPS RO, and the equilibrium thermodynamics of supercooled ternary solutions and ice clouds
    Atmos. Chem. Phys. doi:10.5194/acp-18-1945-2018, 2018
  4. Sioris, C., A. Malo, C. McLinden and R. D'Amours
    Direct injection of water vapor into the stratosphere by volcanic eruptions
    Geophys. Res. Lett. doi:10.1002/2016gl069918, 2016
  5. Takahashi, H., H. Su and J.H. Jiang
    Error analysis of upper tropospheric water vapor in CMIP5 models using “A-Train” satellite observations and reanalysis data
    Climate Dynamics doi:10.1007/s00382-015-2732-9, 2016
  6. Sandhya, M., S. Sridharan and M.I. Devi
    Tropical upper tropospheric humidity variations due to potential vorticity intrusions
    Annales Geophysicae doi:10.5194/angeo-33-1081-2015, 2015
  7. Stanfield, R.E., J.H. Jiang, X. Dong, B. Xi, H. Su, L. Donner, L. Rotstayn, T. Wu, J. Cole and E. Shindo
    A Quantitative Assessment of Precipitation Associated With the ITCZ in the CMIP5 GCM Simulations Climate Dynamics
    Climate Dynamics doi:10.1007/s00382-015-2937-y, 2015
  8. Vergados, P., A. Mannucci, C. Ao, J.H. Jiang and H. Su
    On the comparisons of tropical relative humidity in the lower and middle troposphere among COSMIC radio occultations and MERRA and ECMWF data sets
    Atmospheric Measurement Techniques doi:10.5194/amt-8-1789-2015, 2015
  9. Pertsev, N., P. Dalin, V. Perminov, V. Romejko, A. Dubietis, R. Balčiunas, K. Černis and M. Zalcik
    Noctilucent clouds observed from the ground: sensitivity to mesospheric parameters and long-term time series
    Earth, Planets and Space doi:10.1186/1880-5981-66-98, 2014
  10. Su, H., J.H. Jiang, C. Zhai, V.S. Perun, J.T. Shen, A.D. Genio, L.S. Nazarenko, L.J. Donner, L. Horowitz, C. Seman, C. Morcrette, J. Petch, M. Ringer, J. Cole, M. Mesquita, T. Iversen, J.E. Kristjansson, A. Gettelman, L. Rotstayn, S. Jeffrey, J.L. Dufresne, M. Watanabe, H. Kawai, T. Koshiro, T. Wu, E.M. Volodin, T. L'Ecuyer, J. Teixeira and G.L. Stephens
    Diagnosis of Regime-dependent Cloud Simulation Errors in CMIP5 Models Using A-Train Satellite Observations
    J. Geophys. Res. doi:10.1029/2012JD018575, 2013
  11. Kishore, P., M.V. Ratnam, S.P. Namboothiri, I. Velicogna, G. Basha, J.H. Jiang, K. Igarashi, S.V.B. Rao and V. Sivakumar
    Global 501S­501N distribution of water vapor observed by COSMIC GPS RO: Comparison with GPS radiosonde, NCEP, ERA-Interim, and JRA-25 reanalysis data sets
    J. Atmos. Solar-Terr. Phys. doi:10.1016/j.jastp.2011.04.017, 2011
  12. L'Ecuyer, T.S. and J.H. Jiang
    Touring the atmosphere aboard the A-Train
    Physics Today doi:10.1063/1.3463626, 2010
  13. Read, W.G., A. Lambert, J. Bacmeister, R.E. Cofield, L.E. Christensen, D.T. Cuddy, W.H. Daffer, B.J. Drouin, E. Fetzer, L. Froidevaux, R. Fuller, R. Herman, R.F. Jarnot, J.H. Jiang, Y.B. Jiang, K. Kelly, B.W. Knosp, L.J. Kovalenko, N.J. Livesey, G.L. Manney, H.M. Pickett, H.C. Pumphrey, K.H. Rosenlof, X. Sabounchi, M.L. Santee, M.J. Schwartz, W.V. Snyder, P.C. Stek, H. Su, L.L. Takacs, R.P. Thurstans, H. Vomel, P.A. Wagner, J.W. Waters, C.R. Webster, E.M. Weinstock and D.L. Wu
    Aura Microwave Limb Sounder upper tropospheric and lower stratospheric H2O and relative humidity with respect to ice validation
    J. Geophys. Res. doi:10.1029/2007JD008752, 2007
  14. Cofield, R.E. and P.C. Stek
    Design and field-of-view calibration of 114-660 GHz optics of the Earth Observing System Microwave Limb Sounder
    IEEE Trans. Geosci. Remote Sensing doi:10.1109/TGRS.2006.873234, 2006
  15. Sherwood, S.C., E.R. Kursinski and W.G. Read
    A distribution law for free-troposphere relative humidity
    J. Climate doi:10.1175/JCLI3978.1, 2006
  16. Waugh, D.W.
    Impact of potential vorticity intrusions on subtropical upper tropospheric humidity
    J. Geophys. Res. doi:10.1029/2004JD005664, 2005
  17. Jiang, J.H., B. Wang, K. Goya, K. Hocke, S.D. Eckermann, J. Ma, D.L. Wu and W.G. Read
    Geographical Distribution and Inter-Seasonal Variability of Tropical Deep Convection: UARS MLS Observations and Analyses
    J. Geophys. Res. doi:10.1029/2003JD003756, 2004
  18. Read, W.G., D.L. Wu, J.W. Waters and H.C. Pumphrey
    A New 147-56 hPa Water Vapor Product from the UARS Microwave Limb Sounder
    J. Geophys. Res. doi:10.1029/2003JD004366, 2004
  19. Read, W.G., D.L. Wu, J.W. Waters and H.C. Pumphrey
    Dehydration in the Tropical Tropopause Layer: Implications from UARS MLS
    J. Geophys. Res. doi:10.1029/2003JD004056, 2004
  20. Salby, M., F. Sassi, P. Callaghan, W. Read and H. Pumphrey
    Fluctuations of Cloud, Humidity, and Thermal Structure near the Tropical Tropopause
  21. Spichtinger, P., K. Gierens and W. Read
    The global distribution of ice-supersaturated regions as seen by the Microwave Limb Sounder
    Q. J. Roy. Meteorol. Soc. doi:10.1256/qj.02.141, 2003
  22. Folkins, I., K.K. Kelly and E.M. Weinstock
    A simple explanation for the increase in relative humidity between 11 and 14 km in the tropics
    J. Geophys. Res. doi:10.1029/2002JD002185, 2002
  23. Folkins, I.
    Origin of Lapse Rate Changes in the Upper Tropical Tropopause
  24. Sassi, F., M. Salby, H.C. Pumphrey and W.G. Read
    Influence of the Madden-Julian Oscillation on upper tropospheric humidity
    J. Geophys. Res. doi:10.1029/2001JD001331, 2002
  25. Spichtinger, P., K. Gierens and W. Read
    The statistical distribution law of relative humidity in the global tropopause region
  26. Pawson, S., L. Takacs, A. Molod, S. Nebuda, M. Chen, W. Read and M. Fiorino
    The Tropical Upper Troposphere and Lower Stratosphere in the GEOS-2 GCM
    Adv. Space Res. doi:10.1016/S0273-1177(01)00214-9, 2001
  27. Read, W.G., J.W. Waters, D.L. Wu, E.M. Stone, Z. Shippony, A.C. Smedley, C.C. Smallcomb, S. Oltmans, D. Kley, H.G.J. Smit, J.L. Mergenthaler and M.K. Karki
    UARS Microwave Limb Sounder Upper Tropospheric Humidity Measurement: Method and Validation
    J. Geophys. Res. doi:10.1029/2000JD000122, 2001
  28. Sassi, F., M. Salby and W.G. Read
    Relationship between upper tropospheric humidity and deep convection
    J. Geophys. Res. doi:10.1029/2001JD900121, 2001